Calendars and time

During the seventeenth century, two calendars were used in the Republic that deviated from each other by no less than ten days: the Gregorian calendar (also known as the ‘New Style’) in the provinces of Holland and Zeeland, and the Julian calendar (the ‘Old Style’) in the other provinces.

This was because Pope Gregory XIII’s calendar reform of 1582, whereby ten days were dropped, was somewhat contested. In general, this calendar was accepted only by Catholics and rejected by Protestants. So it came to pass that England, Protestant Germany and Scandinavia continued to use the Julian calendar for the entire seventeenth century, and sometimes longer.

When the new calendar was introduced, the Netherlands were engaged in an uprising against Spain. The leader of the Rebellion, Prince William of Orange, tried to obtain help from the French, and to this end he convinced the States General to appoint a French Prince, the Duke of Anjou (a Catholic), sovereign of the Netherlands. When the Duke of Anjou tried to introduce the Gregorian calendar in the Netherlands, in line with the policies in France, he was obeyed only by the southern provinces, where Catholics were in power. The northern provinces, united in the Union of Utrecht, and with Protestants in charge, were not interested. Only Holland and Zeeland saw the political necessity of the new calendar and accepted it, under pressure by their stadtholder, William of Orange.

  • Brabant & Zeeland – 14 December 1582 was followed by 25 December 1582
  • Holland – 1 January 1583 was followed by 12 January 1583

To avoid mistaking the correct date, in the seventeenth century it was normal to mention the dates of both calendars. In his personal papers, Christiaan Huygens used the New Style calendar.

While the calendars differed by ten days during the seventeenth century, the difference could amount to as much as five weeks for some Christian holidays, such as Easter and Whitsun, because these were calculated slightly differently in each of the calendars. In 1700, Protestant Germany switched to the so-called ‘Improved Julian’ calendar, which was identical to the Gregorian calendar, with the exception of the calculation of Easter. The Dutch provinces that still used the Julian calendar followed soon after:

  • Gelderland – 30 June 1700 was followed by 12 July 1700
  • Utrecht & Overijssel – 30 November 1700 was followed by 12 December 1700
  • Friesland & Groningen – 31 December 1700 was followed by 12 January 1701
  • Drenthe – 30 April 1701 was followed by 12 May 1701

Because the year 1700 was not a leap year according to the Gregorian calendar, the calendars now differed by 11 days. The slight difference in the calculation of Easter between the Improved Julian and the Gregorian calendars only manifested itself in 1724 and 1744. This led to heated debates in the German provinces; however, the Dutch almanac makers apparently did not know that the calculation could differ occasionally; they simply calculated the date of Easter in their almanacs according to the Gregorian calendar.

England and its dependencies only switched to the Gregorian calendar in 1752 (2 September was followed by 14 September). Sweden and Finland (then part of Sweden) followed the year after (17 February was followed by 1 March). The eastern-Orthodox parts of Europe followed much later again, when the difference between the two calendars had risen to thirteen days: Russia switched in 1918 and Greece in 1923.

Alongside the commonly used month names, from the end of the seventeenth century the following alternative names became more and more popular:

  • Louwmaand – January
  • Sprokkelmaand (gathering month) – February
  • Lentemaand (Spring month) – March
  • Grasmaand (grass month) – April
  • Bloeimaand (flowering month) – May
  • Zomermaand (summer month) – June
  • Hooimaand (haymaking month) – July
  • Oogstmaand (harvest month) – August
  • Herfstmaand (Autumn month) – September
  • Wijnmaand (wine month) – October
  • Slachtmaand (butchering month) – November
  • Wintermaand (winter month) – December

These names, derived from everyday language and referring to particular natural phenomena or agricultural activities, had been introduced in the national calendar in the early 9th century by Charlemagne. From 1809, during the period of the Kingdom of the Netherlands under Louis Napoleon (1806-1810), the use of these names in official documents was even made compulsory.